Flexible plate fixation of bone fractures

ABSTRACT

Embodiments provide methods, apparatuses, and systems for fixation of a fractured bone with a bone plate. In various embodiments, the systems and plates provide elastic suspension of the receiving holes relative to an osteosynthesis plate. This elastic suspension can promote load distribution between the screws that connect a bone segment to the plate, thereby reducing stress risers and load shielding effect. In addition, stress at the screw holes, and within the construct as a whole, is reduced by incorporation of these elastic elements in the plate. Additionally, in some embodiments where fracture healing by callus formation is desired, elastic suspension of the receiving holes relative to the osteosynthesis plate can enable small, controlled amounts of relative motion between bone fragments connected by the plate. This relative motion can promote fracture healing by callus formation.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of and claims priorityto U.S. application Ser. No. 13/166,539, which claims priority to U.S.Provisional Patent Application No. 61/428,745 filed Dec. 30, 2010,entitled “FLEXIBLE PLATE FIXATION OF BONE FRACTURES,” and to U.S.Provisional Patent Application No. 61/357,855 filed Jun. 23, 2010,entitled “FLEXIBLE PLATE FIXATION OF BONE FRACTURES.” This applicationadditionally claims priority to U.S. Provisional Patent Application No.61/594,560 filed Feb. 3, 2012 and entitled “BONE PLATE FOROSTEOSYNTHESIS,” the disclosures of which are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

Embodiments herein relate generally to devices for fixation of afractured bone.

BACKGROUND

Osteosynthesis plates for stabilization of bone fractures are typicallyapplied with bone screws. Traditionally, bone screws were used tocompress a plate onto the bone surface to provide stable fixation. Morerecently, locking plates have been introduced, which typically havethreaded receiving holes for positive, angle-stable engagement with thethreaded head portion of a locking screw. These types of locking plateshave been described in French patent document 742,618; U.S. Pat. No.5,709,686; and U.S. Pat. No. 5,741,258. These locking plates can providemore stable fixation in the ends of weak, osteoporotic bone compared totraditional, non-locking plates.

Clinically, locking plate constructs face two principal challenges thatmay be addressed by the present invention. First, a locked plateconstruct may alter the load distribution in bone, which may eithercause bone resorption in case of load shielding, or bone fracture due toimplant-induced stress risers. Second, the high stiffness of a lockedplate construct can suppress relative displacement between bonefragments, whereby this interfragmentary motion is important to promotethe natural cascade of fracture healing by callus formation. Therefore,overly stiff locking plate constructs may delay or prevent fracturehealing by callus formation.

The present invention addresses both of these challenges. First, elasticsuspension of the receiving holes relative to the osteosynthesis platepromotes load distribution between the screws that connect a bonesegment to the plate, thereby reducing stress risers and load shieldingeffects. Second, elastic suspension of the receiving holes relative tothe osteosynthesis plate enables small, controlled amounts of relativemotion between bone fragments connected by the plate. These controlledamounts of relative motion can promote fracture healing by callusformation.

U.S. Pat. No. 4,943,292 describes the use of a cushion of elasticmaterial between the screw head and the bone plate to reduce constructstiffness and to allow early motion at the fracture site. However, U.S.Pat. No. 4,943,292 can only be practiced with non-locking screws,whereby the plate has to be compressed onto the bone surface. Thisprevents relative motion between the plate and the bone surface requiredto induce axial motion at the fracture site.

To enable relative motion between the plate and the bone surface withnon-locking screws, the use of resorbable or biodegradable materialsspaced between a screw head and a plate (US 201010249850; U.S. Pat. No.4,338,926) has been disclosed. However, this prior art provides relativestiff fixation in the early healing phase where a flexible construct ismost desirable to stimulate formation of a healing callus. Furthermore,the prior art progressively loosens over time as resorption of thebiodegradable material at the screw-plate interface causes an increasinglack of fixation stability.

U.S. Patent Application Publication No. US2011/0118742A1 describes meansfor permanent displacement of a screw hole relative to a bone plate togenerate static compression across the bone fracture spanned by the boneplate. Their invention relies on plastic deformation of the screw hole,and is therefore not suitable for elastic suspension of a screw hole toinduce dynamic motion at a fracture site to stimulate fracture healingby callus formation. Moreover, deformation of a locking screw hole maycompromise the screw-bone interface.

The present invention employs elastic suspension of receiving holes in aplate, whereby the screw hole does not undergo deformation, and wherebysaid receiving holes are threaded to receive locking screws that enableplate elevation over the bone surface. Alternatively, elasticallysuspended receiving hole elements may extend past the lower surface ofthe plate when used with non-locking screws to allow plate suspensionover the bone surface, which is required to support relative motionbetween the plate and the bone surface.

It is therefore beneficial and desirable to stabilize a bone fracturewith the plate of the present invention to enhance load distributionbetween screws, and to promoted fracture site motion when fracturehealing by callus formation is desired.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. Embodimentsare illustrated by way of example and not by way of limitation in thefigures of the accompanying drawings.

FIG. 1A illustrates a top view, a longitudinal cross-sectional view, anda transverse cross-sectional view of an example of a bone plate having arivet paired with symmetrically arranged elastic segments and anon-circular, quasi-rectangular through hole, in accordance with variousembodiments;

FIG. 1B illustrates bottom, perspective and side views of an example ofa rivet for use with the bone plate illustrated in FIG. 1A, wherein therivet has a generally circular head and a threaded, non-circularexpansion portion, in accordance with various embodiments;

FIG. 2A illustrates a perspective assembly view of a bone plate having arivet, a locking screw, and a plate section with symmetrically arrangedelastic segments, in accordance with various embodiments;

FIG. 2B illustrates a partial perspective assembly view of the boneplate illustrated in FIG. 2A, having a rivet, a locking screw, and aplate section with symmetrically arranged elastic segments, inaccordance with various embodiments;

FIG. 2C illustrates a top view of a bone plate having a rectangularrivet, a screw, and a plate section with symmetrically arranged elasticsegments flanking the screw receiving hole on either side, in accordancewith various embodiments;

FIG. 2D illustrates a cross-sectional view of the bone plate of FIG. 2C,in accordance with various embodiments;

FIG. 2E illustrates an exploded perspective view of the bone plate ofFIG. 2C, in accordance with various embodiments;

FIG. 3A illustrates a side view of an example of a screw with a threadthat has a consistent core diameter, but an increased outer diameter inthe vicinity of the screw head, in accordance with various embodiments;

FIG. 3B illustrates a top view of a bone plate having a correspondingthread in the plate hole that extends across the motion gap into theplate, in accordance with various embodiments;

FIG. 3C illustrates a transverse cross-sectional view of a bone platehaving a corresponding thread in the plate hole that extends across themotion gap into the plate, in accordance with various embodiments;

FIG. 4A illustrates a perspective assembly view of an embodiment of abone plate assembly that limits deflection of the screw hole member outof the plane of the plate, while allowing for a controlled amount oftranslation of the screw hole member in the direction of the platelongitudinal axis, in accordance with various embodiments;

FIG. 4B illustrates a transverse cross-sectional view of the bone plateassembly illustrated in FIG. 4A, showing that the threaded feature ofthe screw head extends across the motion gap and into the plate to limitdeflection of the screw hole member out of the plane of the plate, whileallowing for a controlled amount of translation of the screw hole memberin the direction of the plate longitudinal axis, in accordance withvarious embodiments;

FIG. 4C illustrates a partial longitudinal perspective view of the boneplate assembly illustrated in FIG. 4A, in accordance with variousembodiments;

FIG. 4D illustrates a partial transverse perspective view of the boneplate assembly illustrated in FIG. 4A, in accordance with variousembodiments;

FIG. 5A illustrates a top view of an example of a bone plate in whichthe motion gaps adjacent to the screw hole diverge from the top surfaceto the lower surface of the plate, in accordance with variousembodiments;

FIG. 5B illustrates a bottom view of the bone plate shown in FIG. 5A, inaccordance with various embodiments;

FIG. 5C illustrates a perspective view of the bone plate shown in FIG.5A, in accordance with various embodiments;

FIG. 5D illustrates a transverse cross-sectional view of the bone plateshown in FIG. 5A, in accordance with various embodiments;

FIG. 6A illustrates a top view of another example of a bone plate forelastic fixation of a bone fracture, in accordance with variousembodiments;

FIG. 6B illustrates a top view of another bone plate for elasticfixation of a bone fracture for use in combination with cylindrical bonesegments, in accordance with various embodiments;

FIG. 7A illustrates a top view and a cross-sectional side view of anexample of a bone plate for elastic fixation of a bone, shown infunctional but unloaded association with a bone screw affixed to acylindrical bone, in accordance with various embodiments;

FIG. 7B illustrates a top view and a cross-sectional side view of anexample of a bone plate for elastic fixation of a bone, shown infunctional loaded association with a bone screw affixed to a cylindricalbone, in accordance with various embodiments;

FIG. 8A illustrates a top view of an embodiment of a C-shaped flexibleelement, in accordance with various embodiments;

FIG. 8B illustrates a top view of another embodiment of a C-shapedflexible element wherein elastic beam elements are narrow to reducestiffness, in accordance with various embodiments;

FIG. 8C illustrates a top view of another embodiment of a C-shapedflexible element wherein the elastic beam elements are elongated toreduce stiffness, in accordance with various embodiments;

FIG. 8D illustrates a top view of an E-shaped flexible element whereinelastic beam elements are narrow to reduce stiffness, in accordance withvarious embodiments;

FIG. 8E illustrates a top view of a flexible element that includes oneE-shaped slot in combination with multiple linear slots, in accordancewith various embodiments;

FIG. 9A illustrates a top view of a flexible element that includes acurvilinear E-shaped slot in combination with multiple linear slots, inaccordance with various embodiments;

FIG. 9B illustrates a perspective view of a bone plate for elasticfixation of a bone fracture, incorporating the flexible elements shownin FIG. 9A, in accordance with various embodiments;

FIG. 10A illustrates a top view of a flexible element that includes asingle spiral-shaped slot, in accordance with various embodiments;

FIG. 10B illustrates a top view of a flexible element that includes asingle spiral-shaped slot with curvilinear and round elements on theoutside and inside spiral ends, respectively, in accordance with variousembodiments;

FIG. 10C illustrates a top view of a flexible element that includes asingle spiral-shaped slot having a thin beam, in accordance with variousembodiments;

FIG. 10D illustrates a top view of a flexible element that includes apair of interlaced spiral-shaped slots, wherein the flexible element isoffset from the midline of the bone plate, in accordance with variousembodiments;

FIG. 10E illustrates a top view of a flexible element that includes apair of interlaced spiral-shaped slots, wherein the flexible element ispositioned at the midline of the bone plate, in accordance with variousembodiments;

FIG. 10F illustrates a top view of a flexible element that includesthree interlaced spiral-shaped slots, in accordance with variousembodiments;

FIG. 11A illustrates a side view of a bone plate Wherein the flexibleelement is a separate, removable element that is configured to beinserted into an enlarged receiving hole, in accordance with variousembodiments;

FIG. 11B illustrates a top view of the flexible element of FIG. 11A, inaccordance with various embodiments;

FIG. 11C illustrates a perspective view of the flexible element of FIG.11A wherein the flexible element is a separate, removable element thatis configured to be inserted into an enlarged receiving hole, inaccordance with various embodiments;

FIG. 12 illustrates a cross-sectional perspective view of a flexibleelement, showing the ratio of beam width to plate height, in accordancewith various embodiments;

FIG. 13A illustrates several views of a flexible element coupled with arivet configured to protect the flexible element from excessivedeformation perpendicular to the plane of the plate, in accordance withvarious embodiments;

FIG. 13B illustrates several views of a flexible element coupled with ahalf-rivet configured to protect the flexible element from excessivedeformation perpendicular to the plane of the plate, in accordance withvarious embodiments;

FIG. 13C illustrates a perspective view of a half rivet configured toprotect the flexible element from excessive deformation perpendicular tothe plane of the plate, wherein the half-rivet is coupled with acustomized bone screw, in accordance with various embodiments;

FIG. 14A illustrates a cross-sectional view of a rivet elasticallysuspended inside a receiving hole in a bone plate using a discretespring element, in accordance with various embodiments;

FIG. 14B illustrates a perspective view of a rivet elastically suspendedinside a receiving hole in a bone plate using a discrete spring element,in accordance with various embodiments;

FIG. 15A illustrates a transverse cross-sectional view of a threadedinsert that is suspended with spring elements in a central positionwithin a receiving hole, whereby the spring elements are rigidly coupledto or part of a threaded insert, in accordance with various embodiments;

FIG. 15B illustrates a top view of the device shown in FIG. 15A, inaccordance with various embodiments;

FIG. 15C illustrates a partial cutaway view of the device shown in FIG.15A, showing placement of an insert, in accordance with variousembodiments;

FIG. 15D illustrates a planar cross-sectional view of the device shownin FIG. 15A, in accordance with various embodiments;

FIG. 16A illustrates a top view of a threaded insert that is generatedfrom the bone plate by introducing a slot that circumscribes thereceiving hole, in accordance with various embodiments;

FIG. 16B illustrates a schematic view of the device shown in FIG. 16A,in accordance with various embodiments;

FIG. 16C illustrates a longitudinal cross-sectional view of the deviceshown in FIG. 16A, in accordance with various embodiments;

FIG. 16D illustrates a transverse cross-sectional view of the deviceshown in FIG. 16A, in accordance with various embodiments;

FIG. 17A illustrates a transverse cross-sectional view of a threadedinsert formed by the introduction of a slot that circumscribes thereceiving hole in an antiparallel manner and suspended (centered) insidea bone plate using flexible elements, in accordance with variousembodiments;

FIG. 17B illustrates a top view of the device illustrated in FIG. 17A,in accordance with various embodiments;

FIG. 17C illustrates a longitudinal cross-sectional view of the deviceillustrated in FIG. 17A, in accordance with various embodiments;

FIG. 18A illustrates a cross-sectional side view of a bone plate forelastic fixation of a bone fracture, shown in functional but unloadedassociation with locking bone screws for spanning a bone fracture in acylindrical bone, in accordance with various embodiments;

FIG. 18B illustrates a cross-sectional side view of a bone plate forelastic fixation of a bone fracture, shown in functional associationwith locking bone screws for spanning a bone fracture in a cylindricalbone, wherein axial compression of the cylindrical bone segments inducesparallel motion at the fracture, in accordance with various embodiments;

FIG. 19A illustrates a cross-sectional side view of a bone plate forelastic compression of a bone fracture, shown in functional associationwith non-locking bone screws for spanning a bone fracture in acylindrical bone, wherein bone screws are inserted in an eccentricmanner, in accordance with various embodiments;

FIG. 19B illustrates a cross-sectional side view of a bone plate forelastic compression of a bone fracture, wherein tightening ofeccentrically inserted bone screws induces elastic compression across abone fracture by deformation of elastic beam elements that connect theplate holes to the plate member, in accordance with various embodiments;and

FIG. 20 is a graph comparing axial stiffness of a standard plate withthat of a plate with spring elements (“S-Plate”) in accordance withembodiments herein.

FIG. 21A illustrates a top view of a device including a receiving holein association with the bone plate of an embodiment incorporating anelastomer lumen partially filling the slot of a flexible elementcoupling the receiving hole to the bone plate.

FIG. 21B illustrates a longitudinal cross-sectional view of the deviceshown in FIG. 21A.

FIG. 21C illustrates a transverse cross-sectional view of the deviceshown in FIG. 21A.

FIG. 22A illustrates a top view of a device including a receiving holein association with a bone plate of an embodiment incorporating anelastomer lumen completely filling the slot of a flexible elementcoupling the receiving hole to the bone plate, wherein the slot fullycircumscribes the periphery of the receiving hole, and whereby the slotsegments are configured in an anti-parallel manner to aid confinement ofthe receiving hole within the plate.

FIG. 22B illustrates a bottom view of the device shown in FIG. 22A.

FIG. 22C illustrates a transverse cross-sectional view of the deviceshown in FIG. 22A.

FIG. 22D illustrates a longitudinal cross-sectional view of the deviceshown in FIG. 22A.

FIG. 23A illustrates a longitudinal cross-sectional view of a receivinghole element that extends past the bone-facing surface of the plate,shown in association with a non-locking bone screw used for compressionof the receiving hole element onto the bone surface.

FIG. 23B illustrates a transverse cross-sectional view of a receivinghole element that extends past the bone-facing surface of the plate,shown in association with a non-locking bone screw,

FIG. 24A illustrates a longitudinal cross-sectional view of a rivet-likereceiving hole element that is elastically suspended in the bone plateby means of an elastomer interface.

FIG. 24B illustrates a transverse cross-sectional view of a rivet-likereceiving hole element that is captured in the plate by means ofexpanded upper and lower sections that overlap in part a mid-section ofthe plate.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which are shownby way of illustration embodiments that may be practiced. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope. Therefore,the following detailed description is not to be taken in a limitingsense, and the scope of embodiments is defined by the appended claimsand their equivalents.

Various operations may be described as multiple discrete operations inturn, in a manner that may be helpful in understanding embodiments;however, the order of description should not be construed to imply thatthese operations are order dependent.

The description may use perspective-based descriptions such as up/down,back/front, and top/bottom. Such descriptions are merely used tofacilitate the discussion and are not intended to restrict theapplication of disclosed embodiments.

The terms “coupled” and “connected,” along with their derivatives, maybe used. It should be understood that these terms are not intended assynonyms for each other. Rather, in particular embodiments, “connected”may be used to indicate that two or more elements are in direct physicalcontact with each other. “Coupled” may mean that two or more elementsare in direct physical or electrical contact. However, “coupled” mayalso mean that two or more elements are not in direct contact with eachother, but yet still cooperate or interact with each other.

For the purposes of the description, a phrase in the form “A/B” or inthe form “A and/or B” means (A), (B), or (A and B). For the purposes ofthe description, a phrase in the form “at least one of A, B, and C”means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).For the purposes of the description, a phrase in the form “(A)B” means(B) or (AB) that is, A is an optional element.

The description may use the terms “embodiment” or “embodiments,” whichmay each refer to one or more of the same or different embodiments.Furthermore, the terms “comprising,” “including,” “having,” and thelike, as used with respect to embodiments, are synonymous.

In various embodiments, methods, apparatuses, and systems for fixationof a fractured bone are provided. In various embodiments, the systemsand plates may provide elastic suspension of receiving holes relative toan osteosynthesis plate. In various embodiments, this elastic suspensionmay promote load distribution between screws that connect a bone segmentto the plate, thereby reducing stress risers and the load shieldingeffect. In addition, in various embodiments, stress at the screw holes,and within the construct as a whole, may be reduced by incorporation ofthese elastic elements in the plate. Additionally, in some embodiments,for instance if fracture healing by callus formation. is desired,elastic suspension of the receiving holes relative to the osteosynthesisplate may enable small, controlled amounts of relative motion betweenbone fragments connected by the plate, which may promote fracturehealing by callus formation. In some embodiments, relative motionbetween bone fragments enabled by the elastic elements may besubstantially parallel to an upper or lower surface of the bone plate,or substantially parallel to a bone surface. This elastic suspension maybe achieved through the use of an elastomer material, such as medicalgrade silicone, as a spacer and spring element.

In some embodiments, elastic suspension is achieved through the use ofspring elements or elastic beam elements. These spring elements orelastic beam elements may be at least partially comprised of metal,which may be supplemented with an elastomer fill material The spacesurrounding the spring elements or elastic beam elements may be at leastpartially filled with an elastomer material in order to preventbottoming out or straining of the element, which can lead to breaking.This elastomer material may be, for example, a medical grade siliconepolymer.

It will be appreciated that the elastomer material may be used in anyembodiment described herein by at least partially filling any gaps orspaces between components used with the bone plates.

Unlike other devices, bone plates in accordance with certain embodimentsdisclosed herein may he configured to be suspended above the surface ofthe bone, so that a gap is present between the lower surface of theplate and the upper surface of the bone. In various embodiments, thismay be accomplished by using locking screws that are designed to engagewith a threaded hole in the bone plate. In various embodiments, thecoupling of a locking screw with a corresponding portion of a bone platemay ensure that the locking screw is only inserted to a certain extent,for instance the point where the screw locks into the hole of the boneplate. In another embodiment, the receiving hole elements may extendthrough the lower surface of the bone plate, for instance so that theplate remains suspended over the bone surface even if a bone fastener isused to compress the receiving hole element to the one bone.

In other embodiments, for instance if direct fracture healing isdesired, elastic suspension of the receiving holes relative to theosteosynthesis plate may promote elastic compression across a fracturesite, whereby the plate may be affixed to the bone with non-lockingscrews inserted in an eccentric manner in order to induce compressionacross the fracture. Thus, in various embodiments, it may be beneficialand desirable to stabilize a bone fracture with a plate as disclosedherein to enhance load distribution between screws, to promote fracturesite motion when fracture healing by callus formation is desired, and/orto induce prolonged compression across a fracture when direct fracturehealing is desired.

FIG. 1A illustrates a top view, a longitudinal cross-sectional view, anda transverse cross-sectional view of a specific, non-limiting example ofa bone plate having a rivet paired with symmetrically arranged elasticsegments and a non-circular, quasi-rectangular through hole; FIG. 1Billustrates bottom, perspective and side views of an example of a rivetfor use with the bone plate illustrated in FIG. 1A, wherein the rivethas a generally circular head and a threaded, non-circular expansionportion.

FIGS. 2A and 2B illustrate a perspective assembly view and across-sectional assembly view of a bone plate having a rivet, a lockingscrew, and a plate section with symmetrically arranged elastic segments,all in accordance with various embodiments. In the example illustratedin FIGS. 1A, 1B, 2A, and 2B, the bone plate 101 may include a rivet 160with generally symmetrically-arranged elastic segments 108 and anon-circular, quasi-rectangular through hole 136. As illustrated,elastic segments (also referred to herein as elastic elements, elasticbeam elements, and spring elements) 108 formed by slots or channels 106may be generally symmetrically-arranged in proximity of the screw hole105, for example to enable translation of the screw hole member 105 a ina principally axial direction. In various embodiments, screw hole member105 a may include quasi-rectangular through hole 136. In variousembodiments, a lower rivet member 160 with a rivet head 148 and arectangular expansion element 168 may be inserted from the lower platesurface 103 into rectangular through hole 136 of screw hole member 105a. In some embodiments, rivet 160 may be secured in screw hole member105 a by press-fit, whereas in other embodiments, rivet 160 may besecured in screw hole member 105 a using a retaining feature that may beadapted to engage with a corresponding receiving feature inquasi-rectangular through hole 136. In various embodiments, rivet head148 may be sufficiently large to extend laterally across the motion gap107 of elastic segments 108. In various embodiments, rivet 160 may beconfigured to protect elastic segments 108 from excessive deformationperpendicular to the plane of plate 101.

In various embodiments, the circular through-hole 105 of rivet 160 maybe threaded, and the threads may extend into quasi-rectangular throughhole 136 of screw hole member 105 a. In various embodiments, a screw 110with matching threads may be inserted from the upper plate surface 102through the rivet 160, and the screw locking feature 109 may besufficiently large to extend laterally across motion gap 107 of elasticsegments 108. Thus, in various embodiments, the screw locking feature109 may therefore limit deflection of screw hole member 105 a towardlower plate surface 103. Additionally or alternatively, in someembodiments, the rivet head 148 may limit deflection of screw holemember 105 a toward upper plate surface 102. Thus, the illustratedexample may enable controlled translation of screw hole member 105 arelative to the longitudinal axis of the plate, yet may limittranslation relative to the plane of bone plate 101 when screw holemember 105 a is guided between the screw locking feature 109 and rivethead 148.

Another example of a bone plate 201 that includes a rivet 260 is shownin FIGS. 2C, 2D, and 2E, which illustrate a top view (FIG. 2C), across-sectional view FIG. 2D), and an exploded perspective view (FIG.2E) of a bone plate having a rectangular rivet 260, a screw 210, and aplate 201 with generally symmetrically arranged elastic segments 208flanking the screw receiving hole on either side, all in accordance withvarious embodiments. In this embodiment, rivet 260 may have arectangular or square shape, and may be recessed into the top and orbottom surfaces of bone plate 201. In some embodiments, rivet 260 mayinclude a separate center shaft portion 268, and one or two shoulderportions 248 coupled thereto, in various embodiments, the upper and/orlower shoulder portions 248 of rivet 260 may limit translation ofreceiving hole 205 in a direction that is substantially perpendicular tothe upper or lower plane of bone plate 201. In other words, rivet 260may constrain out-of-plane motion, while still allowing axial (e.g.,in-plane) translation of receiving hole 205 relative to bone plate 201(or vice versa). In some embodiments, screw 210 may be a locking screw,for instance, a screw having a threaded head portion, or it may be anon-locking screw. In some embodiments, a non-locking screw may compressshoulder portions 248 and center shaft portion 268 of rivet 260 onto thebone, while plate 201 may retain an axially flexible connection with thebone via elastic segments 208.

FIGS. 3A, 3B, and 3C illustrate a side view, a top view, and atransverse cross-sectional view, respectively, of an example of a screwwith a thread that has a consistent core diameter, but an increasedouter diameter in vicinity of the screw head, and FIGS. 4A, 4B, 4C, and4D illustrate a perspective assembly view, a transverse cross-sectionalview, a partial longitudinal perspective view, and a partial transverseperspective view, respectively, of an embodiment of a bone plateassembly 301, showing that the threaded feature of the screw headextends across the motion gap and into the plate to limit deflection ofthe screw hole member out of the plane of the plate, while allowing fora controlled amount of translation of the screw hole member in thedirection of the plate longitudinal axis, all in accordance with variousembodiments.

As discussed above and as illustrated in FIGS. 3 and 4, a bone plate inaccordance with the present disclosure may include elastic segments 308that may be symmetrically arranged in proximity with the screw hole 305,for instance to enable translation of the screw hole member 305 a in aprincipally axial direction. In some embodiments, screw hole member 305a may be guided to remain within the plane of the plate by a thread 321that may extend from screw hole 305, across the motion gap 307, and intothe plate member 301. In some embodiments, thread 321 may becharacterized by an outer diameter that is considerably larger than thecore diameter. For example, a suitable core diameter is in the range of2 to 5 and a suitable outer diameter is in the range of 4 to 10.

In various embodiments, the locking screw 310 may include acorrespondingly threaded head segment 318 with an outer diameter that isconsiderably larger than the core diameter. However, in variousembodiments, the outer diameter of the thread 319 of the screw headsegment 318 may be smaller than the outer diameter of thread 321 inscrew hole member 305 a. In various embodiments, the outer diameter ofthread 319 in screw head segment 318 may remain large enough to extendacross the motion gap 307 and into the plate member 301, once insertedinto the screw hole 305. In some embodiments, screw head 328 may includea locking feature 309 at may enable rigid fixation of screw head 328inside screw hole member 305 a. In particular embodiments, once screw310 is fixed to screw hole member 305 a, screw hole member 305 a maytranslate in a principally axial direction relative to the platelongitudinal axis, for instance, due to the difference in outerdiameters between screw head 328, thread 319, and plate thread 321.However, in some embodiments, extension of screw head thread 319 acrossmotion gap 307 and into plate member 301 may limit deflection of screwhole member 305 a outside the plane of plate 301.

FIGS. 5A, 5B, 5C, and 5D illustrate, a top view, a bottom view, aperspective view, and a transverse cross-sectional view, respectively,of an example of a bone plate 501 in Which the motion gaps 507 adjacentto the screw hole 505 diverge from the top surface 502 to the lowersurface 503 of plate 501, in accordance with various embodiments. In theillustrated example, elastic segments 508 may be symmetrically arrangedin proximity with screw hole 505, for instance, to enable translation ofthe screw hole member 505 a in a principally axial direction. In variousembodiments, motion gaps 507 connecting symmetrically arranged elasticsegments 508 may diverge from (angle away from) the upper plate surface502 toward the lower plate surface 503. In various embodiments, thesedivergent motion gaps 507 may limit deflection of screw hole member 505a through upper surface 502 of the plate member 501. In someembodiments, the head diameter of the corresponding locking screw 510may be sufficiently large to extend over motion gap 507 on upper surface502 of plate member 501. For example, the head may extend over motiongap, when at rest, by about 0.1 mm-3 mm, for example, about 1 mm. Invarious embodiments, the locking feature 509 may thereby limitdeflection of screw hole member 505 a through bottom surface 503 ofplate member 501. Motion gaps 507 shown in FIGS. 5A-5D may be at leastpartially filled with an elastomer material, such as medical gradesilicone. This elastomer fill material provides added stability, elasticsuspensions of the receiving hole, and it reduces or prevents metal onmetal contact between the various elements to minimize wear.

FIG. 6A illustrates a top view of another example of a bone plate forelastic fixation of a bone fracture, and FIG. 6B illustrates a top viewof a further bone plate for elastic fixation of a bone fracture for usein combination with cylindrical bone segments, in accordance withvarious embodiments. In these embodiments, the bone plate 601 may havean upper surface 602 and a bone contacting surface 603, and it maydefine a longitudinal axis 604. In some embodiments, at least onereceiving hole 605 for a fixation element may extend through the uppersurface 602 and the bone contacting surface 603. In some embodiments,receiving hole 605 may be threaded for rigid engagement of a lockingscrew with a threaded head portion, or it may have a concave recess toaccommodate a conventional compression screw. In some embodiments,receiving holes 605 may be disposed along the longitudinal axis 604 asshown in FIG. 6A. In other embodiments, receiving holes 605 may bespaced from the longitudinal axis 604, as shown in FIG. 6B.

Also included in some embodiments, in the vicinity of receiving hole 605are one or more slots 606 extending from the upper surface 602 to thebone contacting surface 603. In various embodiments, at least onesubstantially C-shaped, E-shaped, or semi-circular slot 606 may extendaround a substantial portion of receiving hole 605. In some embodiments,a corresponding slot 606 a may extend from the opposite side of theperiphery around receiving hole 605. In some embodiments, the endsegments of slot 606 may overlap, but not intersect the end segments ofcorresponding slot 606 a. Thus, in various embodiments, the overlappingslots 606 and 606 a may enclose elastic beam elements (e.g., springelements) 608 that may enable elastic translation of receiving hole 605relative to bone plate 601 in a direction principally parallel to thelongitudinal axis 604 of bone plate 601.

In the embodiment illustrated in FIG. 6B elastic beam elements 608 maybe formed by combining at least one substantially C-shaped, E-shaped orsemicircular slot 606 with one or more substantially linear slots 606 aextending from the periphery of bone plate 601 in an essentiallyperpendicular manner to overlap but not intersect with the ends of slots606.

FIGS. 7A and 7B illustrate top and cross-sectional side views of anexample of a bone plate 701 for elastic fixation of a bone, shown infunctional but unloaded (FIG. 7A) association with a bone screw 710affixed to a cylindrical bone 726, and shown in functional loaded (FIG.7B) association with a bone screw 710 affixed to a cylindrical bone, inaccordance with various embodiments. In the illustrated embodiment, alocking bone screw 710 is illustrated that may have a threaded headsegment 718 for rigid engagement with receiving hole 705. In variousembodiments, the screw 710 may be furthermore engaged in first cortex713 and/or second cortex 714 of a substantially cylindrical bone 726,FIG. 7A illustrates an example of an unloaded construct, and FIG. 7Billustrates an example of how a load acting through bone 726 and ontolocking screw 710 may induce translation of receiving hole 705 relativeto the bone plate 701 by elastic deformation of elastic beam elements708 between receiving hole 705 and bone plate 701.

In various embodiments, the dimensions and/or the configuration of thespring elements (e.g., elastic beam elements) and/or slots may be variedin order to achieve a desired stiffness and range of elasticdisplacement of the bone plate relative to the receiving holes. FIG. 8Adepicts an embodiment with thicker beam elements 808 as compared to beamelements 808 shown in. FIG. 8B, the latter allowing for more flexibledisplacement of receiving hole 805 relative to bone plate member 801,Another example of a way to decrease the stiffness of the elasticelements is depicted in FIG. 8C, wherein the length of slot 806 isincreased in order to increase the effective length of beam elements808. Yet another example of a way to decrease the stiffness of theelastic element is depicted in FIG. 8D, wherein slots 806 are configuredin a substantially E-shaped formation, which may yield an increasedeffective length of elastic beam elements 808. Another alternativeembodiment of an elastic element is depicted in FIG. 8E, whereinreceiving hole 805 is located in vicinity of plate edge 823. In thisexample, two slots 806 may overlap but not intersect each end of aC-shaped slot 806 to form elastic beam elements 808.

FIG. 9A illustrates a top view of a flexible element that includes acurvilinear E-shaped slot in combination with multiple linear slots 906,and FIG. 9B illustrates a perspective view of a bone plate 901 forelastic fixation of a bone fracture that incorporates the flexibleelements 908 shown in FIG. 9A, in accordance with various embodiments.As illustrated in FIG. 9A, some embodiments of bone plates 901 playinclude one curvilinear E-shaped slot 906 b in combination with multiplelinear slots 906 a, which together form elastic beam elements 908. Insome embodiments, the curvilinear slots 906 a may reduce peak stress andprovide a more even strain distribution when loaded along thelongitudinal axis of a bone plate 901. This embodiment is similar tothat shown in FIG. 8D, in that the elastic beam elements 908 may befolded back on themselves. In some embodiments, each of the two foldedelastic beams 908 associated with a receiving hole 905 may be orientedin opposite directions, wherein the folded end of one elastic beamelement 908 may be oriented toward the edge of the bone plate 901, andthe folded end of the other elastic beam element may be oriented towardthe bone plate 901 midline. In various embodiments, the curvilinear foldof the elastic beam element 908 may fit closely within the E-shaped slot906 b, which arrangement may contribute to a stable association ofreceiving hole 905 with plate 901, while still allowing for controlledaxial translation of receiving hole 905 relative to plate 901. FIG. 9Billustrates a perspective view of a bone plate having the curvilinearE-shaped slots 906 b shown in FIG. 9A. In this embodiment, the receivingholes 905 may be offset from the longitudinal axis, which may contributeto the stability and stiffness of bone plate 901.

Some embodiments of the flexible fixation bone plates may includecurvilinear and/or spiral-shaped slots. FIG. 10A illustrates a top viewof a flexible element that includes of a single spiral-shaped slot 1006,FIG. 10B illustrates a top view of a flexible element that includes asingle spiral-shaped slot 1006 with curvilinear 1016 and round elements1018 on the outside and inside spiral ends, respectively, FIG. 10Cillustrates a top view of a flexible element that includes a singlespiral-shaped slot 1006 having a thin elastic beam element 1008, FIG.10D illustrates a top view of a flexible element that includes a pair ofinterlaced spiral-shaped slots 1006, wherein the flexible element isoffset from the midline of the bone plate 1001, FIG. 10E illustrates atop view of a flexible element that includes a pair of interlacedspiral-shaped slots 1006, wherein the flexible element is positioned atthe midline of the bone plate 1001, and FIG. 10F illustrates a top viewof a flexible element that includes three interlaced spiral-shaped slots1006, all in accordance with various embodiments.

FIG. 10A depicts another embodiment of an elastic element. In thisembodiment, a single spiral-shaped slot 1006 may be positioned aroundreceiving hole 1005. In various embodiments, the spiral slot 1006 maycircumscribe receiving hole 1005 once or multiple times, creatingelastic beam element 1008 where it overlaps. In various embodiments, inorder to reduce stress concentrations at the spiral ends, circular 1018or curvilinear 1016 elements may be added to the ends of slot 1006 asshown in FIG. 10B, or the beam elements 1008 may be tapered. As with theembodiments shown in FIG. 8A and 8B, in various embodiments, beamelements 1008 may be configured to be thinner, as shown in FIG. 10C,allowing for more flexible displacement of receiving hole 1005 relativeto bone plate member 1001. In various embodiments, increasing the lengthof spiral beam element 1008 also may allow for increased flexibility.

As shown in FIGS. 10D and 10E, receiving holes 1005 may be located alongthe midline of plate 1001, or at a distance from the longitudinal axisof plate 1001. For example, in various embodiments, if receiving holes1005 are arranged in an alternating staggered pattern relative to thelongitudinal midline of plate 1001, they may provide multi-planarfixation to improve the strength of the fixation between plate 1001 andthe underlying bone. Both FIGS. 10D and 10E illustrate spiral slots 1006that include two interlaced spirals. One of skill in the art willappreciate that additional spiral slots 1006 may be used, such as thethree-slot 1006 arrangement depicted in FIG. 10F.

FIGS. 11A, 11B, and 11C illustrate three views of another embodiment ofa flexible element. In this embodiment of bone plate 1101, slot 1106 andelastic beam element 1108 may be located on a separate, removable plugelement 1120 that may be adapted to be inserted into an enlargedreceiving hole 1136. In an alternate embodiment, removable plug element1120 may be an integral component of an enlarged head of a bone screwthat engages the correspondingly enlarged receiving hole 1136.

FIG. 12 depicts a cross-sectional perspective view of anotherembodiment, showing the dimensions of beam element 1208 and slot 1206.Generally, beam elements 1208 may be considerably higher (thicker) thanthey are wide. For instance, in some embodiments, the ratio of the beamheight 1264 to the beam width 1266 may vary from about 2 (2 to 1) toabout 12 (12 to 1), for instance from about 6 (6 to 1) to about 9 (9 to1). In various embodiments, receiving holes 1205 associated withflexible elements as described herein may or may not have features forpositive locking of a bone screw or fastener. For instance, inembodiments lacking positive locking mechanisms, the flexible springelement may act to relieve stress at the plate-bone interface, Inembodiments having positive locking mechanisms, the flexible element mayprovide flexible plate fixation to allow small relative motion betweenthe plate and the bone, which in turn may induce interfragmentary motionand promote bone healing.

In further embodiments, FIG. 13A illustrates several views of a flexibleelement 1308 used in conjunction with a rivet 1340 configured to protectthe flexible element 1308 from excessive deformation perpendicular tothe plane of the plate 1301, FIG. 13B illustrates several views of aflexible element 1308 used in conjunction with a half-rivet 1360configured to protect the flexible element 1308 from excessivedeformation perpendicular to the plane of the plate 1301, and. FIG. 13Cillustrates a perspective view of a half rivet 1360 configured toprotect the flexible element 1308 from excessive deformationperpendicular to the plane of the plate 1301, wherein the half-rivet1360 is used together with a customized bone screw 1310, all inaccordance with various embodiments.

As illustrated in FIG. 13A, the elastic element 1308 may include aspiral-shaped slot 1306 positioned around receiving hole 1305, and thespiral slot 1306 may circumscribe receiving hole 1305 once or multipletimes, creating elastic beam element 1308 where it overlaps, In thisembodiment, a rivet 1338 may be provided in receiving hole 1305, and maybe configured to protect elastic beam element 1308 from excessivedeformation perpendicular to the plane of plate 1301. In variousembodiments, rivet 1338 may have a shoulder 1348 on each side of acentral cylinder 1340 to restrict flexion of elastic beam element 1308that may occur within the plane of plate 1301. In embodiments, the innerdiameter of the central cylinder 1340 of rivet 1338 may be threaded forrigid locking with the threaded head of a bone screw 1310. Depending onplate 1301 thickness, the rivet shoulders 1348 may rest on the surfaceof the plate 1301, or may be recessed into the plate 1301. In variousembodiments wherein shoulder 1348 is recessed, the longitudinaldimension of the recess may be larger than the corresponding dimensionof rivet shoulder 1348 to allow rivet translation along the plate 1301longitudinal axis, while constraining rivet 1338 translation in atransverse direction.

In various embodiments, for assembly, rivet 1338 may include two partsthat may be inserted from opposite sides into receiving hole 1305, andthe two parts may be rigidly coupled to each other, for instance bylaser welding or by a thread feature between central cylinder 1340 andshoulder 1348. Alternatively, as illustrated in FIG. 13B, rivet 1338 mayhave only one shoulder 1348 to form a “half-rivet” 1360, which may limitdeformation of elastic beam element 1308 in only one direction. Invarious embodiments, half-rivet 1360 may include an externally threadedcentral cylinder 1340 for rigid engagement to elastic beam element 1308.Alternatively, in some embodiments, half-rivet 1360 may be attached toelastic beam element 1308 using a press fit between central cylinder1340 and elastic beam element 1308. In embodiments, half-rivet 1360 maybe used in combination with a customized bone screw 1310 as shown inFIG. 13C, which may include a head that incorporates a correspondingshoulder element 1362. Thus, in various embodiments, upon screwinsertion, elastic beam element 1308 may be confined between shoulder1348 of half-rivet 1360 and the corresponding shoulder 1362 of the screwhead, with the remainder of the screw head resting inside centralcylinder 1340 of half-rivet 1360.

In various other embodiments shown in FIGS. 14A and 14B, rivet 1438 maybe elastically suspended inside receiving hole 1436 using a discretespring element 1458. In some embodiments, spring element 1458 mayinclude a corrugated metal strip 1444, that may circumscribe centralcylinder 1440 of rivet 1438, and that may center rivet 1438 insidereceiving hole 1436, while allowing for elastic translation of rivet1438 within the plane of plate 1401. This spring element including acorrugated metal strip may be supplemented with an elastomer fillmaterial, which at least partially fills the space between rivet 1438and plate 1401 to provide additional elastic suspension and damping, andto prevent bottoming out, wear or excessive deformation of springelement 1458. In other embodiments, the spring element 1458 may includean elastomer material, such as a silicone derivative, that provides ahyper-elastic interface, filling space in the receiving hole between thecentral cylinder 1440 of rivet 1438 and plate 1401. In some embodiments,spring element 1458 may further retain rivet 1438 inside the plane ofplate 1401. The inner diameter of central cylinder 1440 of rivet 1438may be threaded in some embodiments for rigid locking with the threadedhead of a bone screw.

FIGS. 15 A, 15B, 15C, and 15D illustrate a cross-sectional view, a topview, a partial cutaway view showing placement of an insert 1546, and aplanar cross-sectional view, respectively, of another embodiment, inwhich a threaded insert 1546, once inserted into insert receiving hole1536, may translate along the longitudinal plate axis within the planeof plate 1501. In various embodiments, threaded insert 1546 may besuspended with spring elements (e.g., flexible elements) 1548 in acentral position within insert receiving hole 1536, whereby springelements (e.g., flexible elements) 1548 may be rigidly coupled to orpart of threaded insert 1546. In other embodiments, the threaded insertmay be suspended by an elastomer material, such as a siliconederivative, that provides a hyper-elastic interface, filling spacebetween the threaded insert 1548 and the plate 1501. In someembodiments, opposite sides of threaded insert 1546 may have a convexcylindrical surface 1550 adapted to securely retain threaded insert 1546within the plane of plate 1501. In various embodiments, forinstallation, threaded insert 1546 may be first rotated perpendicular tothe plate surface, then inserted into insert receiving hole 1536, andfinally rotated by 90 degrees so that its upper surface is parallel tothe upper surface of plate 1501. In some embodiments, spring elements(e.g., flexible elements) 1548 may engage with (e.g., snap into) acorresponding recess 1542 in plate 1501 to ensure that upon insertion,threaded insert 1546 remains rotationally secured within the plane ofplate 1501.

In further embodiments, FIG. 16A illustrates a top view of a threadedinsert 1646 that is generated from the bone plate 1601 by introducing aslot 1606 that circumscribes the receiving hole 1605, FIG. 16Billustrates a schematic view of the device shown in FIG. 16A, FIG. 16Cillustrates a longitudinal cross-sectional view of the device shown inFIG. 16A, and FIG. 16D illustrates a transverse cross-sectional view ofthe device shown in FIG. 16A, all in accordance with variousembodiments. As illustrated in various embodiments, a threaded insert1646 may be generated from plate 1601 by introducing a slot 1606 thatcircumscribes receiving hole 1605. In various embodiments, slot 1606 maybe introduced in an anti-parallel manner, whereby two opposing sections1652 of slot 1606 converge toward the lower side 1603 of plate 1601,while two other opposing sections 1654 diverge toward the lower side1603 of plate 1601. Hence, in these embodiments, the anti-parallel slot1606 may enable threaded insert 1646 to translate relative to plate 1601within the confines of the slot width, and without being able todisassociate from plate 1601. The space between the threaded insert 1646and the plate 1601 may be filled with an elastomer material. Thiselastomer material may comprise an elastic silicone derivative, whichmay act as a spacer and a spring between the threaded insert and plate,providing an elastic suspension of the threaded insert.

In still other embodiments, FIG. 17A illustrates a transversecross-sectional view of a threaded insert 1746 formed by theintroduction of a slot 1706 that circumscribes the receiving hole 1705in an anti-parallel manner and suspended (centered) inside a bone plate1701 using flexible elements 1758, FIG. 17B illustrates a top view ofthe device illustrated in FIG. 17A, and FIG. 17C illustrates alongitudinal cross-sectional view of the device illustrated in FIG. 17A,all in accordance with various embodiments. As illustrated in FIGS.17A-C, threaded insert 1746 may be formed by the introduction of a slot1706 that circumscribes receiving hole 1705 in an antiparallel manner asdescribed above, and threaded insert 1746 may be suspended (centered)inside plate 1701 using flexible elements 1758. In an exemplaryembodiment, these flexible elements 1758 may be cylindrical in shape andcomprised of a polymer, and may provide a flexible connection betweenthreaded insert 1746 and plate 1701, while the anti-parallel slotensures that threaded insert 1746 remains securely captured in plate1701. In other embodiments, the threaded insert may be suspended by anelastomer material, such as a silicone derivative, that provides ahyper-elastic interface, filling a space between the threaded insert1746 and the plate 1701.

In other embodiments, FIG. 18A illustrates a cross-sectional side viewof a bone plate for elastic fixation of a bone fracture, shown infunctional but unloaded association with locking bone screws forspanning a bone fracture in a cylindrical bone, and FIG. 18B illustratesa cross-sectional side view of a bone plate for elastic fixation of abone fracture, shown in functional association with locking bone screwsfor spanning a bone fracture in a cylindrical bone, wherein axialcompression of the cylindrical bone segments induces parallel motion atthe fracture, both in accordance with various embodiments.

Thus, in order to illustrate a method for elastic fixation of a bonefracture, FIG. 18A depicts a cross-sectional view of an embodiment forelastic fixation of a bone fracture 1824 with a bone plate 1801 that maybe attached to two bone segments 1826. In this configuration, each bonesegment 1826 may be connected by one or more locking bone screws 1810 toreceiving holes 1805 that may be connected with elastic elements 1808 tobone plate 1801. In embodiments, the screw heads 1828 of bone screws1810 may be rigidly connected to receiving holes 1805, for instance bymatching thread features on screw heads 1828 with those on the receivingholes 1805. In embodiments, this locking mechanism between screw heads1828 and receiving holes 1805 may enable bone plate 1801 to remainelevated above bone surface 1830, while providing elastic fixationbetween bone segments 1826.

In order to illustrate a method for inducing principally parallel axialmotion across a bone fracture, FIG. 18B depicts a cross-sectional viewof an embodiment for elastic fixation of a bone fracture subjected toaxial loading, as may be the case in patients that start weight bearingof a fractured extremity that has been stabilized with bone plate 1801.In various embodiments, the load acting on bone segments 1826 and ontolocking screws 1810 may induce elastic translation of receiving holes1805 relative to bone plate 1801, which in turn may cause generallyparallel motion between bone segments 1826 at bone fracture 1824. Inthis configuration, axial loading of bone segments 1826 may causeelastic deformation of elastic beam elements 1808, wherein slot segments1832 located at the aspect of receiving hole 1805 facing fracture 1824become narrower, while slot segments 1834 located at the receiving holeaspect facing away from fracture 1824 become wider.

In various other embodiments, FIG. 19A illustrates a cross-sectionalside view of a bone plate for elastic compression of a bone fracture,shown in functional association with non-locking bone screws forspanning a bone facture in a cylindrical bone, wherein bone screws areinserted in an eccentric manner, and FIG. 19B illustrates across-sectional side view of a bone plate for elastic compression of abone fracture, wherein tightening of eccentrically inserted bone screwsinduces elastic compression across a bone fracture by deformation ofelastic beam elements that connect the plate holes to the plate member,both in accordance with various embodiments.

Thus, in order to illustrate a method for inducing elastic compressionacross a bone fracture, FIGS. 19A and 19B depict cross-sectional viewsof an embodiment of a bone plate 1901 applied to bridge and toelastically compress a fracture 1924 in a substantially cylindricalbone. FIG. 19A depicts bone screws 1910 being partially inserted throughreceiving holes 1905 into bone segments 1926. In various embodiments,screws 1910 may be inserted eccentrically in receiving holes 1905, at asmall distance from the center-line 1922 of receiving hole 1905 in anopposite direction from fracture 1924. FIG. 19B depicts the embodimentin a cross-sectional view after complete insertion of screws 1910. Sincescrews 1910 were inserted eccentrically relative to receiving hole 1905,once screw heads 1928 are contacting bone plate 1901 during insertion,screws 1910 may he forced to translate toward the center of receivingholes 1905. This in turn causes bone segment 1926 attached to screws1910 to translate relative to bone plate 1901 toward fracture 1924,thereby inducing compression across fracture 1924. Once fracture 1924 isfully compressed, any further translation may be accommodated bydeformation of elastic beam elements 1908 connecting receiving holes1905 to bone plate 1901. In embodiments, this elastic deformation mayinduce additional compressive forces at fracture 1924.

As illustrated in FIG. 20, the introduction of elastic elements in abone plate as described elsewhere herein (referred to in FIG. 20 as anS-plate) may reduce axial stiffness of the plate as compared to astandard plate without the elastic elements. Notably, there is little tono impact on the bending stiffness of the plate due to the introductionof the elastic elements.

FIGS. 21A-21C show an exemplary embodiment wherein slots in the vicinityof the receiving hole are at least partially filled with an elastomermaterial. FIG. 21A illustrates a top view of a receiving hole inassociation with the bone plate, FIG. 21B illustrates a longitudinalcross-sectional view of the device shown in FIG. 21A, and FIG. 21Cillustrates a transverse cross-sectional view of the device shown inFIG. 21A. Bone plate 2101 has an upper surface 2102, a bone contactingsurface 2103, and defines a longitudinal axis 2104. At least onereceiving hole 2105 for a fixation element extends through the uppersurface 2102 and the bone contacting surface 2103. Receiving hole 2105may be threaded for rigid engagement of a locking screw with a threadedhead portion. In the vicinity of receiving hole 2105 are two interlacedspiral slots 2106 extending from the upper surface 2102 to the bonecontacting surface 2103. The two interlaced segments of spiral slots2106 form elastic beam elements 2107 that enable elastic translation ofreceiving hole 2105 relative to bone plate 2101. In this embodiment, oneor both slots are at least partially filled with an elastomer 2108(shown in solid black) to supplement elastic suspension of receivinghole 2105 in bone plate 2101. This elastomer may comprise a medicalgrade silicone or equivalent substance.

Elastomer lumen 2108 provides several attributes to support elastictranslation of receiving hole 2105 relative to plate 2101 in directionparallel to the upper surface 2102 of plate 1. First, it prevents directcontact between adjacent surfaces of spiral slots 2106 to eliminatewear. Second, it prevents excessive displacement of spiral beams 2107,which could otherwise lead to excessive deformation and early fatigue ofthe spiral beams 2107. Third, the elastomer lumen 2108 supplements theelastic connection provided by elastic beams 2107 between receiving hole2105 and bone plate 2101 to achieve a desired suspension stiffness.Fourth, elastomer lumen 2108 dampens the transfer of impact load fromreceiving hole 2105 to plate 2101.

This elastomer lumen 2108 may supplement control of translation ofreceiving hole 2105 relative to plate 2101 in a direction perpendicularto the upper surface 2102 of plate 2101. When used for this purpose,elastomer lumen 2108 may be configured to positively adhere to thesurface of slots 2106 to affect a desired elastic constraint ofreceiving hole 2105 relative to bone plate 2101.

An alternative embodiment of bone plate 2201 according to the presentinvention is shown in FIGS. 22A-22D, wherein the receiving hole issuspended in the plate by an elastomer lumen at least partially fillinga slot surrounding the receiving hole. FIG. 22A illustrates a top viewof a receiving hole 2205 in association with bone plate 2201, FIG. 22Billustrates a bottom view of the device shown in FIG. 22A, FIG. 22Cillustrates a transverse cross-sectional view of the device shown inFIG. 22A, and FIG. 22D illustrates a longitudinal cross-sectional viewof the device shown in FIG. 22A, all in accordance with variousembodiments. As illustrated in various embodiments, slot 2206 fullycircumscribes receiving hole 2205 and extends from upper surface 2202 tothe bone-contacting surface 2203 of plate 2201, In contrast to theembodiment shown in FIGS. 21A-21C, there are no remaining flexible beamsthat connect hole 2205 within plate 2201. Instead, receiving hole 2205is suspended in the plate by means of an elastomer lumen 2208, which maycomprise a silicone lumen, filling slot 2206. Slot 2206 surroundingreceiving hole 2205 is wider in longitudinal plate direction 2204compared to the transverse direction 2209 to accommodate preferentialtranslation of receiving hole 2205 in direction parallel to long axis2204 of the plate, while substantially limiting rotation and translationof the receiving hole in a plane that is perpendicular to platelongitudinal axis 2204. The elastomer lumen 2208 may be configured topositively adhere to at least a portion of the surface of slot 2206 toaffect a desired elastic constraint of receiving hole 2205 relative tobone plate 2201. As an alternative means to retain receiving hole 2205in plate 2201, slot 2206 surrounding receiving hole 2205 may beintroduced in an anti-parallel manner, whereby the two opposing sections2210 of slot 2206 converge toward lower side 2203 of plate 2201, whiletwo other opposing sections 2211 diverge toward lower side 2203 of plate2201. The anti-parallel slot 2206 may enable receiving hole 2205 totranslate relative to plate 2201 within the confines of the width ofslot 2206, or within the constraints provided by the elastomer lumen2208 in slot 2206, but without being able to disassociate from plate2201, Based on the geometry of slot 2206, receiving hole member 2205 maybe created from plate 2201 by cutting said slot 2206 in a manner topermanently retain receiving hole member 2205 in plate 2201. In analternative embodiment, receiving hole member 2201 may be manufacturedas a separate component that is rotationally inserted into acorresponding slot 2206 in plate 2201, and is subsequently suspended inplate 2201 by means of an injectable and curable elastomer lumen 2208.

FIGS. 23A-B illustrate a cross-sectional view of a receiving holeelement 2305 that extends past bone-facing surface 2303 of plate 2301,shown in association with a non-locking bone screw 2310 used forcompression of receiving hole element 2305 onto bone surface 2313. Inthis configuration the bone-facing surface 2303 of plate 2301 remainselevated over bone surface 2313, even when receiving hole element 2305is being compressed onto bone surface 2313. A non-locking screw 2310 canbe used to connect plate 2301 to bone 2326 by direct compression ofreceiving hole element 2305 onto bone surface 2313. In conjunction withan elastic suspension 2308 of receiving holes 2305 in plate 2301, suchplate elevation over bone surface 2313 enables relative motion betweenplate 2301 and bone surface 2313. Elastic suspension 2308 may comprisean elastomer material, such as a medical grade silicone or equivalentsubstance. Hence, non-locking bone screws 2310 can be used to achieve anelastic plating construct for induction of controlled motion at thefracture. The envelope of elastic suspension 2308 is wider in thelongitudinal cross-sectional view (FIG. 23A) than in the transversecross-sectional view (FIG. 23B), since elastic translation of receivinghole element 2305 relative to plate 2301 is primarily desired parallelto the longitudinal axis of plate 2301.

FIGS. 24A-B illustrate a cross-sectional view of a rivet-like receivinghole element 2405 that is captured in plate 2401 by means of expandedupper and lower sections 2404 that overlap in part a mid-section 2406 ofplate 2401. The slot 2408 between receiving hole element 2405 and plate2401 is filled at least in part with an elastomer. This elastomer maycomprise a medical grade silicone or equivalent substance. The primaryfunction of this elastomer envelope formed in slot 2408 is to provide anelastic suspension of receiving hole element 2405 in bone plate 2401.The particular design of receiving hole element 2405 with expanded upperand lower sections 2404 limits the motion of receiving hole element 2405perpendicular to plate surface 2403 and prevents disassociation ofreceiving hole element 2405 from plate 2401. The expanded sections 2404of receiving hole element 2405 may only overlap a mid-section 2406 ofthe plate in a transverse cross-section, as shown in FIG. 24B. In thelongitudinal cross-section of FIG. 24A, the expanded sections 2404 maynot overlap a mid-section of the plate in the unloaded position to allowfor translation of receiving hole element 2405 along the longitudinalaxis of plate 2401.

In some embodiments, the bone plate may have a through hole configuredto receive a removable threaded rivet insert. The insert is temporarilyconfined within the hole by means of a snap mechanism. Insertion of abone screw into the threaded rivet insert disables the snap mechanism toprevent disengagement of the rivet from the through hole in the boneplate. Elastic suspension of the threaded rivet insert within the boneplate hole may be achieved by applying an elastomer coating to at leasta part of the plate hole surface, the periphery of the rivet, or both.

In some embodiments, having an opening with a major dimension in atransverse direction may effectively reduce the bending strength of boneplates, which may fail in bending. Thus in various embodiments, theflexible elements described herein may not have a major dimensionextending in transverse direction. This orientation may cause the boneplate to retain a substantial amount of bending strength. As describedelsewhere herein, it is desirable to maintain the bending strength ofthe construct while reducing the axial stiffness of plate, andadditionally reducing stress at the screw hole(s) and in the constructas a whole. In various embodiments, stress at the screw hole(s) maycause undesirable or detrimental deformation of the hole(s).

In some embodiments, if the cantilever beam were located transversely‘in-line’ with the screw hole, the transverse opening may extend over asubstantial portion of the plate in order to derive flexibility, whichin turn may reduce the bending strength of the plate. Thus, variousembodiments disclosed herein employ a combination of two or morecantilever beams located above and below the screw hole (e.g., in thelongitudinal plate direction), which may preserve bending strength ofthe plate.

In some embodiments described herein, one or more pairs of cantileverbeams may be employed, wherein the beams of each cantilever pair arelocated on opposite sides of the screw hole in longitudinal direction,rather than one cantilever beam element that extends in a principallytransverse direction to either one or both sides of the screw hole(lug), depending if the screw hole is located offset from or located onthe longitudinal plate midline, respectively.

Some embodiments disclosed herein use pairs of slots that extend throughthe plate edge, rather than a slot that defines the transverse openingand that surrounds the beam and lug element, wherein the slot remainswithin the plate surface and does not extend through the plate edge.

Some embodiments include a set of slots per screw hole, wherein the setcombines a central slot that partially surrounds the screw hole withoutextending through the plate edge with peripheral slots that penetratethrough the longitudinal plate edge, rather than one continuous slot perscrew hole, whereby the slot defines the transverse opening andsurrounds the beam and lug element.

Various other embodiments disclosed herein employ a set of slots to forma principally S-shaped spring element having an upper and a lowercantilever element that is diagonally connected by a central segmentthat contains the screw hole, rather than a generally I-shapedcantilever beam, for instance. Still other embodiments described hereinemploy cantilever elements of a width that is substantially smaller thanthe plate thickness, rather than a cantilever element of a width that islarger than the plate thickness. This may ensure a desired bendingdirection of the cantilever beam within the plane of the plate ratherthan out of the plane of the plate.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. Specifically, the disclosed invention may bepracticed for fixation of a bone plate to one side of a fracture only,whereby the corresponding side of a fractured bone may be applied to theone plate by alternative means for flexible or rigid fixation. It isunderstood, therefore, that this disclosure is not limited to theparticular embodiments disclosed, but it is intended to covermodifications within the spirit and scope of the present disclosure asdefined by the appended claims.

Although certain embodiments have been illustrated and described herein,it will be appreciated by those of ordinary skill in the art that a widevariety of alternate and/or equivalent embodiments or implementationscalculated to achieve the same purposes may be substituted for theembodiments shown and described without departing from the scope. Thosewith skill in the art will readily appreciate that embodiments may beimplemented in a very wide variety of ways. This application is intendedto cover any combinations, adaptations, or variations of the embodimentsdiscussed herein. Therefore, it is manifestly intended that embodimentsbe limited only by the claims and the equivalents thereof.

What is claimed is:
 1. A device, comprising: a bone fracture fixation plate having an upper surface and a bone-facing surface, the bone plate comprising one or more slots extending through the plate from the upper surface to the bone-facing surface, the one or more slots at least partially circumscribing a periphery of one or more receiving holes to enable relative displacement between the receiving holes within the bone plate, wherein the one or more slots are at least partially filled with an elastomer to support elastic suspension of said receiving holes in the bone plate. 